244 W. H. HOBBS ORIGIN OF OCEAN BASINS 



such records are to seismology. Cables are found to have been repeat- 

 edly interrupted at the same points, and since in many districts they run 

 in nearly parallel lines, the opportunity is afforded of locating with some 

 definiteness the zone of displacement whenever the interruptions may be 

 traced to this source.* Thus on October 4, 1884, three transatlantic 

 cables were interrupted simultaneously at the base of the steep eastern 

 slope of the continental shelf (Flemish cap) 330 miles from Saint John, 

 New Brunswick. The cables run in parallel lines 10 miles apart and the 

 fractured places lay opposite each other in a straight line,f probably in- 

 dicating the considerable differential movement on the scarp. These and 

 other cables have been repeatedly fractured at the same point. Thus the 

 cable from Lipari to Milazzo, Sicily, has been five times interrupted at 

 the same point, sometimes during known earthquakes, as during the 

 great Calabrian earthquake of September 8, 1905. The other interrup- 

 tions occurred November 21 and 23, 1888, March 30, 1889, September 

 11, 1889 (all during activity of volcano 3 miles away), and February 

 9, 1893. J Cable companies have given out but little regarding the 

 interruptions of their cables, which nearly always occur during shocks 

 in near-lying territory. Enough is known to say that there is here a 

 mine of valuable data on the behavior of the sea-floor at the time of 

 earthquakes. Out of 245 breaks of cables discussed by Milne 87 occurred 

 at times when instruments were in operation which would record "unfelt" 

 earthquakes; 58 of the 87 interruptions occurred at or about the times 

 when unfelt quakes were registered at European stations. 



Forstee's Observations on sudden Changes in the Mediterranean 



Floor 



Much the most important observations that have yet been made directly 

 upon sea-bottom changes are those of Mr Porster,§ the manager and elec- 

 trician of the Eastern Cable Company at Zante, Greece. The fact that a 

 large part of the Mediterranean floor in late Tertiar^f time constituted 

 with the large islands a broad bridge connecting Europe to Africa ;|| the 

 complex fault system present in both the Italian and Balkan peninsulas ; 



* To note how large a part of the sea-floor is now crossed by cables, see a new map 

 of the cable lines of the world (ownership given), which has recently been issued from 

 the Geographical Institute of C. Opitz, Leipzig, published in the Deutsche lUustrirte 

 Zeitung of March 1, 1906. 



t Milne : Loc. cit, p. 262. 



t W. H. Hobbs : Notes on a trip to the Lipari islands. Trans. Wis. Acad. Sci., vol. 9, 

 1893, p. 664. 



§ W. G. Forster : Seismology, London, 188'^, pp. 68. Reviewed by R. D. Salisbury in 

 American Geologist, vol. .3, 1889, pp. 182-188. 



II See Wm. Herbert Hobbs : The geotectonic and geodynamic aspects of Calabria and 

 northeastern Sicily. Gerland's Beitrage zur Geophysik, vol. 8, pp. 293-362, 10 pis. 



